<?
/*
diff.php

Copyright (C) 1992 Free Software Foundation, Inc. Francois Pinard <pinard@iro.umontreal.ca>.
Copyright (C) 2000, 2001 Geoffrey T. Dairiki <dairiki@dairiki.org>
Copyright 2002,2003,2004 David DELON
Copyright 2002 Patrick PAUL
Copyright 2003 Eric FELDSTEIN

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
// Side : a string for wdiff

class Side {
	var $position;
	var $cursor;
	var $content;
	var $character;
	var $directive;
	var $argument;
	var $length;

	function Side($content) {
		$this->content=$content;
		$this->position=0;
		$this->cursor=0;
		$this->directive='';
		$this->argument=array();
		$this->length=strlen($this->content);
		$this->character=substr($this->content,0,1);

	}

	function getposition() {
		return $this->position;
	}

	function getcharacter() {
		return $this->character;
	}

	function getdirective() {
		return $this->directive;
	}

	function getargument() {
		return $this->argument;
	}

	function nextchar() {
		$this->cursor++;
		$this->character=substr($this->content,$this->cursor,1);
	}

	function copy_until_ordinal($ordinal,&$out) {
		while ($this->position < $ordinal) {
			$this->copy_whitespace($out);
			$this->copy_word($out);
		}
	}

	function skip_until_ordinal($ordinal) {
		while ($this->position < $ordinal) {
			$this->skip_whitespace();
			$this->skip_word();
		}
	}

	function split_file_into_words (&$out) {
		while (!$this->isend()) {
			$this->skip_whitespace();
			if ($this->isend()) {
				break;
			}
			$this->copy_word($out);
			$out .="\n";
		}
	}

	function init() {
		$this->position=0;
		$this->cursor=0;
		$this->directive='';
		$this->argument=array();
		$this->character=substr($this->content,0,1);
	}

	function isspace($char) {
		if (preg_match("/([[:space:]]|\*)/",$char)) return true;
		return false;
	}

	function isdigit($char) {
		if (preg_match('/[[:digit:]]/',$char)) return true;
		return false;
	}

	function isend() {
		if (($this->cursor)>=($this->length)) return true;
		return false;
	}

	function copy_whitespace(&$out) {
		while (!$this->isend() && $this->isspace($this->character)) {
			$out .=$this->character;
			$this->nextchar();
		}
	}

	function skip_whitespace() {
		while (!$this->isend() && $this->isspace($this->character)) {
			$this->nextchar();
		}
	}

	function skip_line() {
		while (!$this->isend() && !$this->isdigit($this->character)) {
			while (!$this->isend() && $this->character!="\n")
				$this->nextchar();
			if($this->character=="\n")
				$this->nextchar();
		}
	}

	function copy_word(&$out) {
		while (!$this->isend() && !($this->isspace($this->character))) {
			$out.=$this->character;
			$this->nextchar();
		}
		$this->position++;
	}

	function skip_word() {

		while (!$this->isend() && !($this->isspace($this->character))) {
			$this->nextchar();
		}
		$this->position++;
	}


	function decode_directive_line() {

		$value=0;
		$state=0;
		$error=0;

		while (!$error && $state < 4) {
			if ($this->isdigit($this->character)) {
				$value = 0;
				while($this->isdigit($this->character)) {
					$value = 10 * $value + $this->character - '0';
					$this->nextchar();
				}
			}
			else if ($state != 1 && $state != 3)
				$error = 1;

			/* Assign the proper value. */

			$this->argument[$state] = $value;

			/* Skip the following character. */

			switch ($state) {
			case 0:
			case 2:
				if ($this->character == ',')
					$this->nextchar();
				break;

			case 1:
				if ($this->character == 'a' || $this->character == 'd' || $this->character == 'c') {
					$this->directive = $this->character;
					$this->nextchar();
				}
				else
				$error = 1;
				break;

			case 3:
				if ($this->character != "\n")
					$error = 1;
				break;
			}
			$state++;
		}

		/* Complete reading of the line and return success value. */

		while ((!$this->isend()) && ($this->character != "\n")) {
			$this->nextchar();
		}
		if ($this->character == "\n")
			$this->nextchar();

		return !$error;
	}



}

// difflib
//
// A PHP diff engine for phpwiki.
//
// Copyright (C) 2000, 2001 Geoffrey T. Dairiki <dairiki@dairiki.org>
// You may copy this code freely under the conditions of the GPL.
//


// PHP3 does not have assert()
define('USE_ASSERTS', function_exists('assert'));

class _DiffOp {
	var $type;
	var $orig;
	var $final;

	function norig() {
		return $this->orig ? sizeof($this->orig) : 0;
	}

	function nfinal() {
		return $this->final ? sizeof($this->final) : 0;
	}
}

class _DiffOp_Copy extends _DiffOp {
	var $type = 'copy';

	function _DiffOp_Copy ($orig, $final = false) {
		if (!is_array($final))
			$final = $orig;
		$this->orig = $orig;
		$this->final = $final;
	}

}

class _DiffOp_Delete extends _DiffOp {
	var $type = 'delete';

	function _DiffOp_Delete ($lines) {
		$this->orig = $lines;
		$this->final = false;
	}

}

class _DiffOp_Add extends _DiffOp {
	var $type = 'add';

	function _DiffOp_Add ($lines) {
		$this->final = $lines;
		$this->orig = false;
	}

}

class _DiffOp_Change extends _DiffOp {
	var $type = 'change';

	function _DiffOp_Change ($orig, $final) {
		$this->orig = $orig;
		$this->final = $final;
	}

}


/**
* Class used internally by Diff to actually compute the diffs.
*
* The algorithm used here is mostly lifted from the perl module
* Algorithm::Diff (version 1.06) by Ned Konz, which is available at:
* http://www.perl.com/CPAN/authors/id/N/NE/NEDKONZ/Algorithm-Diff-1.06.zip
*
* More ideas are taken from:
* http://www.ics.uci.edu/~eppstein/161/960229.html
*
* Some ideas are (and a bit of code) are from from analyze.c, from GNU
* diffutils-2.7, which can be found at:
* ftp://gnudist.gnu.org/pub/gnu/diffutils/diffutils-2.7.tar.gz
*
* Finally, some ideas (subdivision by NCHUNKS > 2, and some optimizations)
* are my own.
*
* @author Geoffrey T. Dairiki
* @access private
*/
class _DiffEngine
{
	function diff ($from_lines, $to_lines) {
		$n_from = sizeof($from_lines);
		$n_to = sizeof($to_lines);

		$this->xchanged = $this->ychanged = array();
		$this->xv = $this->yv = array();
		$this->xind = $this->yind = array();
		unset($this->seq);
		unset($this->in_seq);
		unset($this->lcs);

		// Skip leading common lines.
		for ($skip = 0; $skip < $n_from && $skip < $n_to; $skip++) {
			if ($from_lines[$skip] != $to_lines[$skip])
				break;
			$this->xchanged[$skip] = $this->ychanged[$skip] = false;
		}
		// Skip trailing common lines.
		$xi = $n_from; $yi = $n_to;
		for ($endskip = 0; --$xi > $skip && --$yi > $skip; $endskip++) {
			if ($from_lines[$xi] != $to_lines[$yi])
				break;
			$this->xchanged[$xi] = $this->ychanged[$yi] = false;
		}

		// Ignore lines which do not exist in both files.
		for ($xi = $skip; $xi < $n_from - $endskip; $xi++)
			$xhash[$from_lines[$xi]] = 1;
			for ($yi = $skip; $yi < $n_to - $endskip; $yi++) {
				$line = $to_lines[$yi];
				if ( ($this->ychanged[$yi] = empty($xhash[$line])) )
					continue;
				$yhash[$line] = 1;
				$this->yv[] = $line;
				$this->yind[] = $yi;
			}
			for ($xi = $skip; $xi < $n_from - $endskip; $xi++) {
				$line = $from_lines[$xi];
				if ( ($this->xchanged[$xi] = empty($yhash[$line])) )
					continue;
				$this->xv[] = $line;
				$this->xind[] = $xi;
			}

			// Find the LCS.
			$this->_compareseq(0, sizeof($this->xv), 0, sizeof($this->yv));

			// Merge edits when possible
			$this->_shift_boundaries($from_lines, $this->xchanged, $this->ychanged);
			$this->_shift_boundaries($to_lines, $this->ychanged, $this->xchanged);

			// Compute the edit operations.
			$edits = array();
			$xi = $yi = 0;
			while ($xi < $n_from || $yi < $n_to) {
				USE_ASSERTS && assert($yi < $n_to || $this->xchanged[$xi]);
				USE_ASSERTS && assert($xi < $n_from || $this->ychanged[$yi]);

				// Skip matching "snake".
				$copy = array();
				while ( $xi < $n_from && $yi < $n_to
					&& !$this->xchanged[$xi] && !$this->ychanged[$yi]) {
				$copy[] = $from_lines[$xi++];
				++$yi;
					}
					if ($copy)
						$edits[] = new _DiffOp_Copy($copy);

					// Find deletes & adds.
					$delete = array();
					while ($xi < $n_from && $this->xchanged[$xi])
						$delete[] = $from_lines[$xi++];

					$add = array();
					while ($yi < $n_to && $this->ychanged[$yi])
						$add[] = $to_lines[$yi++];

					if ($delete && $add)
						$edits[] = new _DiffOp_Change($delete, $add);
					elseif ($delete)
						$edits[] = new _DiffOp_Delete($delete);
					elseif ($add)
						$edits[] = new _DiffOp_Add($add);
			}
			return $edits;
	}


	/* Divide the Largest Common Subsequence (LCS) of the sequences
	* [XOFF, XLIM) and [YOFF, YLIM) into NCHUNKS approximately equally
	* sized segments.
	*
	* Returns (LCS, PTS). LCS is the length of the LCS. PTS is an
	* array of NCHUNKS+1 (X, Y) indexes giving the diving points between
	* sub sequences. The first sub-sequence is contained in [X0, X1),
	* [Y0, Y1), the second in [X1, X2), [Y1, Y2) and so on. Note
	* that (X0, Y0) == (XOFF, YOFF) and
	* (X[NCHUNKS], Y[NCHUNKS]) == (XLIM, YLIM).
	*
	* This function assumes that the first lines of the specified portions
	* of the two files do not match, and likewise that the last lines do not
	* match. The caller must trim matching lines from the beginning and end
	* of the portions it is going to specify.
	*/
	function _diag ($xoff, $xlim, $yoff, $ylim, $nchunks) {
		$flip = false;

		if ($xlim - $xoff > $ylim - $yoff) {
			// Things seems faster (I'm not sure I understand why)
			// when the shortest sequence in X.
			$flip = true;
			list ($xoff, $xlim, $yoff, $ylim)
			= array( $yoff, $ylim, $xoff, $xlim);
		}

		if ($flip)
			for ($i = $ylim - 1; $i >= $yoff; $i--)
			$ymatches[$this->xv[$i]][] = $i;
		else
		for ($i = $ylim - 1; $i >= $yoff; $i--)
			$ymatches[$this->yv[$i]][] = $i;

		$this->lcs = 0;
		$this->seq[0]= $yoff - 1;
		$this->in_seq = array();
		$ymids[0] = array();

		$numer = $xlim - $xoff + $nchunks - 1;
		$x = $xoff;
		for ($chunk = 0; $chunk < $nchunks; $chunk++) {
			if ($chunk > 0)
				for ($i = 0; $i <= $this->lcs; $i++)
				$ymids[$i][$chunk-1] = $this->seq[$i];

			$x1 = $xoff + (int)(($numer + ($xlim-$xoff)*$chunk) / $nchunks);
			for ( ; $x < $x1; $x++) {
				$line = $flip ? $this->yv[$x] : $this->xv[$x];
				if (empty($ymatches[$line]))
					continue;
				$matches = $ymatches[$line];
				reset($matches);
				while (list ($junk, $y) = each($matches))
				if (empty($this->in_seq[$y])) {
					$k = $this->_lcs_pos($y);
					USE_ASSERTS && assert($k > 0);
					$ymids[$k] = $ymids[$k-1];
					break;
				}
				while (list ($junk, $y) = each($matches)) {
					if ($y > $this->seq[$k-1]) {
						USE_ASSERTS && assert($y < $this->seq[$k]);
					// Optimization: this is a common case:
						// next match is just replacing previous match.
						$this->in_seq[$this->seq[$k]] = false;
						$this->seq[$k] = $y;
						$this->in_seq[$y] = 1;
					}
					else if (empty($this->in_seq[$y])) {
						$k = $this->_lcs_pos($y);
						USE_ASSERTS && assert($k > 0);
						$ymids[$k] = $ymids[$k-1];
					}
				}
			}
		}

		$seps[] = $flip ? array($yoff, $xoff) : array($xoff, $yoff);
		$ymid = $ymids[$this->lcs];
		for ($n = 0; $n < $nchunks - 1; $n++) {
			$x1 = $xoff + (int)(($numer + ($xlim - $xoff) * $n) / $nchunks);
			$y1 = $ymid[$n] + 1;
			$seps[] = $flip ? array($y1, $x1) : array($x1, $y1);
		}
		$seps[] = $flip ? array($ylim, $xlim) : array($xlim, $ylim);

		return array($this->lcs, $seps);
	}

	function _lcs_pos ($ypos) {
		$end = $this->lcs;
		if ($end == 0 || $ypos > $this->seq[$end]) {
			$this->seq[++$this->lcs] = $ypos;
			$this->in_seq[$ypos] = 1;
			return $this->lcs;
		}

		$beg = 1;
		while ($beg < $end) {
			$mid = (int)(($beg + $end) / 2);
			if ( $ypos > $this->seq[$mid] )
				$beg = $mid + 1;
			else
			$end = $mid;
		}

		USE_ASSERTS && assert($ypos != $this->seq[$end]);

		$this->in_seq[$this->seq[$end]] = false;
		$this->seq[$end] = $ypos;
		$this->in_seq[$ypos] = 1;
		return $end;
	}

	/* Find LCS of two sequences.
	*
	* The results are recorded in the vectors $this->{x,y}changed[], by
	* storing a 1 in the element for each line that is an insertion
	* or deletion (ie. is not in the LCS).
	*
	* The subsequence of file 0 is [XOFF, XLIM) and likewise for file 1.
	*
	* Note that XLIM, YLIM are exclusive bounds.
	* All line numbers are origin-0 and discarded lines are not counted.
	*/
	function _compareseq ($xoff, $xlim, $yoff, $ylim) {
		// Slide down the bottom initial diagonal.
		while ($xoff < $xlim && $yoff < $ylim
			&& $this->xv[$xoff] == $this->yv[$yoff]) {
		++$xoff;
		++$yoff;
			}

			// Slide up the top initial diagonal.
			while ($xlim > $xoff && $ylim > $yoff
				&& $this->xv[$xlim - 1] == $this->yv[$ylim - 1]) {
			--$xlim;
			--$ylim;
				}

				if ($xoff == $xlim || $yoff == $ylim)
					$lcs = 0;
					else {
						// This is ad hoc but seems to work well.
						//$nchunks = sqrt(min($xlim - $xoff, $ylim - $yoff) / 2.5);
						//$nchunks = max(2,min(8,(int)$nchunks));
						$nchunks = min(7, $xlim - $xoff, $ylim - $yoff) + 1;
						list ($lcs, $seps)
						= $this->_diag($xoff,$xlim,$yoff, $ylim,$nchunks);
					}

					if ($lcs == 0) {
						// X and Y sequences have no common subsequence:
						// mark all changed.
						while ($yoff < $ylim)
							$this->ychanged[$this->yind[$yoff++]] = 1;
						while ($xoff < $xlim)
							$this->xchanged[$this->xind[$xoff++]] = 1;
					}
					else {
						// Use the partitions to split this problem into subproblems.
						reset($seps);
						$pt1 = $seps[0];
						while ($pt2 = next($seps)) {
							$this->_compareseq ($pt1[0], $pt2[0], $pt1[1], $pt2[1]);
							$pt1 = $pt2;
						}
					}
	}

	/* Adjust inserts/deletes of identical lines to join changes
	* as much as possible.
	*
	* We do something when a run of changed lines include a
	* line at one end and has an excluded, identical line at the other.
	* We are free to choose which identical line is included.
	* `compareseq' usually chooses the one at the beginning,
	* but usually it is cleaner to consider the following identical line
	* to be the "change".
	*
	* This is extracted verbatim from analyze.c (GNU diffutils-2.7).
	*/
	function _shift_boundaries ($lines, &$changed, $other_changed) {
		$i = 0;
		$j = 0;

		USE_ASSERTS && assert('sizeof($lines) == sizeof($changed)');
		$len = sizeof($lines);
		$other_len = sizeof($other_changed);

		while (1) {
			/*
			* Scan forwards to find beginning of another run of changes.
			* Also keep track of the corresponding point in the other file.
			*
			* Throughout this code, $i and $j are adjusted together so that
			* the first $i elements of $changed and the first $j elements
			* of $other_changed both contain the same number of zeros
			* (unchanged lines).
			* Furthermore, $j is always kept so that $j == $other_len or
			* $other_changed[$j] == false.
			*/
			while ($j < $other_len && $other_changed[$j])
				$j++;

				while ($i < $len && ! $changed[$i]) {
					USE_ASSERTS && assert('$j < $other_len && ! $other_changed[$j]');
					$i++; $j++;
					while ($j < $other_len && $other_changed[$j])
						$j++;
				}

				if ($i == $len)
					break;

				$start = $i;

				// Find the end of this run of changes.
				while (++$i < $len && $changed[$i])
					continue;

					do {
						/*
						* Record the length of this run of changes, so that
						* we can later determine whether the run has grown.
						*/
						$runlength = $i - $start;

						/*
						* Move the changed region back, so long as the
						* previous unchanged line matches the last changed one.
						* This merges with previous changed regions.
						*/
						while ($start > 0 && $lines[$start - 1] == $lines[$i - 1]) {
							$changed[--$start] = 1;
							$changed[--$i] = false;
							while ($start > 0 && $changed[$start - 1])
								$start--;
							USE_ASSERTS && assert('$j > 0');
							while ($other_changed[--$j])
								continue;
							USE_ASSERTS && assert('$j >= 0 && !$other_changed[$j]');
						}

						/*
						* Set CORRESPONDING to the end of the changed run, at the last
						* point where it corresponds to a changed run in the other file.
						* CORRESPONDING == LEN means no such point has been found.
						*/
						$corresponding = $j < $other_len ? $i : $len;

						/*
						* Move the changed region forward, so long as the
						* first changed line matches the following unchanged one.
						* This merges with following changed regions.
						* Do this second, so that if there are no merges,
						* the changed region is moved forward as far as possible.
						*/
						while ($i < $len && $lines[$start] == $lines[$i]) {
							$changed[$start++] = false;
							$changed[$i++] = 1;
							while ($i < $len && $changed[$i])
								$i++;

							USE_ASSERTS && assert('$j < $other_len && ! $other_changed[$j]');
							$j++;
							if ($j < $other_len && $other_changed[$j]) {
								$corresponding = $i;
								while ($j < $other_len && $other_changed[$j])
									$j++;
							}
						}
					} while ($runlength != $i - $start);

					/*
					* If possible, move the fully-merged run of changes
					* back to a corresponding run in the other file.
					*/
					while ($corresponding < $i) {
						$changed[--$start] = 1;
						$changed[--$i] = 0;
						USE_ASSERTS && assert('$j > 0');
						while ($other_changed[--$j])
							continue;
						USE_ASSERTS && assert('$j >= 0 && !$other_changed[$j]');
					}
		}
	}
}

/**
* Class representing a 'diff' between two sequences of strings.
*/
class Diff
{
	var $edits;

	/**
	* Constructor.
	* Computes diff between sequences of strings.
	*
	* @param $from_lines array An array of strings.
	* (Typically these are lines from a file.)
	* @param $to_lines array An array of strings.
	*/
	function Diff($from_lines, $to_lines) {
		$eng = new _DiffEngine;
		$this->edits = $eng->diff($from_lines, $to_lines);
	}

}



/**
* A class to format Diffs
*
* This class formats the diff in classic diff format.
* It is intended that this class be customized via inheritance,
* to obtain fancier outputs.
*/
class DiffFormatter
{

	/**
	* Format a diff.
	*
	* @param $diff object A Diff object.
	* @return string The formatted output.
	*/
	function format($diff) {

		$xi = $yi = 1;
		$block = false;
		$context = array();

		$this->_start_diff();

		foreach ($diff->edits as $edit) {
			if ($edit->type == 'copy') {
				if (is_array($block)) {
					if (sizeof($edit->orig) <= 0) {
						$block[] = $edit;
					}
					else{
						$this->_block($x0, + $xi - $x0,
							$y0, + $yi - $y0,
							$block);
						$block = false;
					}
				}
			}
			else {
				if (! is_array($block)) {
					$x0 = $xi;
					$y0 = $yi;
					$block = array();
				}
				$block[] = $edit;
			}

			if ($edit->orig)
				$xi += sizeof($edit->orig);
			if ($edit->final)
				$yi += sizeof($edit->final);
		}

		if (is_array($block))
		$this->_block($x0, $xi - $x0,
			$y0, $yi - $y0,
			$block);

		return $this->_end_diff();
	}

	function _block($xbeg, $xlen, $ybeg, $ylen, &$edits) {
		$this->_start_block($this->_block_header($xbeg, $xlen, $ybeg, $ylen));
	}

	function _start_diff() {
		ob_start();
	}

	function _end_diff() {
		$val = ob_get_contents();
		ob_end_clean();
		return $val;
	}

	function _block_header($xbeg, $xlen, $ybeg, $ylen) {
		if ($xlen > 1)
			$xbeg .= "," . ($xbeg + $xlen - 1);
		if ($ylen > 1)
			$ybeg .= "," . ($ybeg + $ylen - 1);

		return $xbeg . ($xlen ? ($ylen ? 'c' : 'd') : 'a') . $ybeg;
	}

	function _start_block($header) {
		echo $header."\n";
	}

}
?>